Genuine OEM Jaguar Water Hose O-Ring, part number 104123524. This small but vital component is designed to create a leak-proof seal at connection points within the engine's cooling system water hoses. Its function is to prevent coolant loss and maintain proper system pressure, which is crucial for effective engine temperature regulation. Choosing a genuine OEM O-ring ensures it is made from the correct material with precise dimensions and elasticity, guaranteeing a durable and reliable seal against temperature fluctuations and chemical exposure.